Low-Density Ferromagnetism in the Hubbard Model

• 来源期刊: 中国物理快报(英文版)
• 学科: 物理学
• 年，卷（期）: 2001,（1）
• 页码范围: 109-110
• 页数: 2页
• 分类号: O4
• 语种: 英文

摘要

We study analytically the stability of the saturated ferromagnetic ground state (the Nagaoka state) of the Hubbard model in the Iow electron density limit with the mean-field approach. We find that the critical Uc is just 4πt, where t is the hopping integral between the nearest neighbours, i.e., when U is larger than 4πt, the paramagnetic state is unstable with respect to the ferromagnetic state, and vice versa.